Urease producing bacteria have been used to remediate the surface and subsurface of permeable media. This process, also known as mineral plugging, has been used in the oil industry where the decreased permeability and porosity of treated media reduces fluid flow and thus can enhance the recovery of oil from reservoirs and/or limit the spread of contaminants from a spill site.
Mineral plugs form as a result of precipitation caused by the increase in pH, which itself is a result of the ammonia formed as a product of the enzymatic breakdown of urea by the urease enzyme. However, whilst these plugs have been used to reduce the porosity/permeability of fissures and other cracks in geological formations, the resulting cement is not strong enough for a range of other applications. Furthermore, the degree of control of the process used to form mineral plugs is limited meaning that results are inconsistent and there are many applications where the method is simply not viable.
Conventional cement is used for a variety of structural applications However, because conventional cement is applied as a fairly thick slurry, it is not adapted for spray application nor is it particularly useful for applications where it is necessary or desirable to form the cement at or below a surface or retain the porosity of the cemented material.
The present invention seeks to address the limitations described above by providing a method for forming a high strength cement using urease producing micro-organisms and defined amounts of other reagents. The present invention also seeks to provide various uses of the high strength cement.